Dynamic regulation of canonical TGFβ signalling by endothelial transcription factor ERG protects from liver fibrogenesis

Heshuxiaoji pill suppresses steatohepatitis and fibrosis by regulating the AngII-BACH1 mediated vasoconstriction

ETHNOPHARMACOLOGICAL RELEVANCE

Non-alcoholic steatohepatitis (NASH), a widespread hepatic affliction marked by hepatic fibrosis progression towards hepatocellular carcinoma, is significantly influenced by endothelial dysfunction and endothelial-to-mesenchymal transition (EndMT). Although Heshuxiaoji (HSXJ) Pill, an empirical prescription formulated by Prof. Tongjiao Sun has demonstrated significant efficacy in mitigating steatohepatitis and fibrosis, the precise mechanisms underlying its therapeutic effects remain to be fully elucidated.

AIM OF THE STUDY

To investigate the antifibrotic effect of HSXJ pill and to explore its mechanism in vivo and in vitro.

MATERIALS AND METHODS

To probe the antifibrotic impact of HSXJ pill and unravel its mechanisms, murine liver fibrosis and NASH models were induced in vivo via Western diet and CCl4 injection. In vitro, human umbilical vein endothelial cells were stimulated with AngII, followed by Western blot analysis. Additionally, liver biopsies from patients with mild-to-moderate fibrosis (S1-S2) were utilized to verify EndMT involvement in fibrosis.

RESULTS

In the hepatocyte sections exhibiting human liver fibrosis, we observed a significant upregulation of AngII and the transcription factor BTB and CNC homology 1 (BACH1). Genetic ablation of AngII significantly ameliorates hepatic fibrosis and EndMT, while attenuating pathological angiogenesis via decreased BACH1 expression. In contrast, AngII overexpression exacerbates these conditions. In vivo, the HSXJ pill effectively alleviates hepatic fibrosis, reduces alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, and suppresses BACH1 and AngII production, thereby inhibiting EndMT. In vitro, the pill mitigates EndMT-associated fibrosis by regulating BACH1 to inhibit AngII activation.

CONCLUSION

The study indicates that the HSXJ pill effectively diminishes hepatocyte injury markers and alleviates liver fibrosis, with optimal efficacy at medium/high doses. BACH1 serves as a key regulator of hepatic fibrosis via modulation of AngII expression.

miR-27b-3p modulates liver sinusoidal endothelium dedifferentiation in chronic liver disease

BACKGROUND

During chronic liver diseases, LSECs undergo a dedifferentiation process contributing to the development of hepatic microvascular dysfunction. Although microRNAs (miRNAs) have been associated with chronic liver disease, their role as modulators of liver endothelial phenotype is mostly unknown. Therefore, the aim of this study was to analyze miRNAs as regulators of hepatic sinusoidal endothelial dysfunction in chronic liver disease to suggest novel and translatable therapeutic options for cirrhosis.

METHODS

Global expression of miRNAs was determined in primary LSECs from healthy and cirrhotic patients (alcohol abuse) and rats (CCl4 inhalation). LSECs were transfected with the mimetic or inhibitor of dysregulated miRNAs or with quantum dot nano-complexes containing miR-27b-3p or negative control, and endothelial phenotype was analyzed by RNA sequencing, quantitative PCR, and western blot. Endothelial or mesenchymal phenotypes were analyzed in LSEC by RNA sequencing, followed by pathway analyses and gene deconvolution.

RESULTS

In all, 30 and 69 dysregulated miRNAs were identified in human and rat cirrhosis, respectively, of which 6 miRNAs were commonly dysregulated. Specific exogenous downregulation of miR-27b-3p was associated with the upregulation of target genes, suggesting a correlation between loss of miR-27b-3p and LSEC dedifferentiation. Finally, the expression of miR-27b-3p was efficiently and physiologically re-established in cirrhotic LSECs using nano-miR-27b-3p, leading to modulation of 1055 genes compared with the negative control, ultimately leading to inhibition of the endothelial-to-mesenchymal transition process observed in cirrhosis.

CONCLUSIONS

Loss of miR-27b-3p expression contributes to LSECs dedifferentiation in cirrhosis. The use of nano-miR-27b-3p represents a new therapeutic option for hepatic diseases coursing with endothelial dysfunction.

A novel EndMT inhibitor, xanthotoxin, attenuates non-alcoholic fatty liver disease by acting as TGFβR2 antagonist

BACKGROUND

Endothelial-to-mesenchymal transition (EndMT) has emerged as a key process contributing to the pathology of non-alcoholic fatty liver disease (NAFLD). Thus, identifying EndMT inhibitors may help impede NAFLD progression.

PURPOSE

Our research aims to identify potent natural EndMT inhibitors and explore their therapeutic potential and mechanisms of action in NAFLD.

METHODS

A natural compound library was employed to screen potential EndMT inhibitors. High-fat diet (HFD)-induced ApoE-/- mice and free fatty acid (FFA)-treated human hepatic sinusoidal endothelial cells (HHSECs) were employed as animal and cellular models of NAFLD. EndMT was evaluated by western blotting, qRT-PCR, immunofluorescence staining, tube formation, wound healing, and transwell assays. LC-MS/MS was applied to screen for altered secreted proteins during EndMT. Molecular docking, CETSA, and SPR assays were employed to validate the combination of xanthotoxin with TGFβR2.

RESULTS

Xanthotoxin was identified as a novel EndMT inhibitor. Further investigation revealed that xanthotoxin ameliorates NAFLD in ApoE-/- mice. By inhibiting EndMT, xanthotoxin improves endothelial dysfunction, reduces the pro-NAFLD factor ANGPTL2 secretion, and increases the anti-NAFLD factor SOD2 secretion, thus reducing hepatocyte steatosis, inflammation, and hepatic stellate cell fibrosis. Additional studies demonstrated that xanthotoxin binds to TGFβR2 and acts as its antagonist to block EndMT. In mice, EC-specific overexpression of TGFβR2 negated xanthotoxin's therapeutic impact on NAFLD.

CONCLUSION

This study reveals for the first time that xanthotoxin attenuates NAFLD by acting as a TGFβR2 antagonist to inhibit EndMT. These findings highlight the significant therapeutic potential of xanthotoxin in NAFLD treatment.

IFN-γ-mediated inhibition of JAK/STAT signaling via nano-scutellarin treatment is an efficient strategy for ameliorating liver fibrosis

BACKGROUND

Metabolic dysfunction-associated steatohepatitis (MASH) is a large group of metabolic diseases that are hazardous to human health. Endothelial-to-mesenchymal transition (EndMT) mediated myofibroblast activation is an important factor that aggravates the development of liver fibrosis during MASH. However, the limited understanding of the underlying molecular mechanisms that drive EndMT in MASH has hindered the development of molecularly targeted therapies specifically targeting this pathological process.

METHODS

We employed wild-type and ifn-γ-deficient mice, MASH models were induced repeated CCl4 injections and a high-fat diet to verify the significance of IFN-γ role in vivo and its impact in EndMT. Male mice models of MASH were used to further analyze the effect of Scutellarin@BSA on the improvement of liver fibrosis during MASH in vivo and HUVECs were used to assess IFN-γ effect on EndMT and its interaction with JAK signaling pathway in vitro.

RESULTS

The results showed that IFN-γ is revealed as a key regulator of EndMT during MASH, as evidenced by the significantly lower levels of EndMT and reduced pathological damage in the livers of ifn-γ knockout mice. Furthermore, our research has led to the development of Scutellarin@BSA therapy, which targets and mitigates IFN-γ-driven EndMT, which showed excellent therapeutic effects on EndMT and liver fibrosis in vivo and in vitro during MASH. Mechanistically, IFN-γ can directly bind to the JAK protein and activate downstream STAT1 transcription factors, exerting transcriptional activity and further driving the expression of EndMT-associated proteins. Notably, Scutellarin@BSA treatment effectively diminishes the hallmarks of liver fibrosis by modulating the canonical JAK/STAT1 signaling pathway.

CONCLUSIONS

IFN-γ was identified as a key regulator of EndMT, and Scutellarin@BSA, as an emerging treatment, has been found to effectively inhibit EndMT by directly targeting the regulatory influence of the IFN-γ signaling. This result demonstrates significant therapeutic efficacy in alleviating hepatic fibrosis during MASH, highlighting its great potential as an innovative liver fibrosis treatment.

Identification of SOX9-related prognostic DEGs and a prediction model for hepatitis C-induced early-stage fibrosis

BACKGROUND

Hepatitis C virus (HCV) infection induces liver inflammation, activating hepatic stellate cells (HSC) and advancing fibrosis. Studies have indicated that SOX9 overexpression is closely linked to HSC activation. The study aims to identify genes associated with SOX9 and search for potential targets for detecting and treating liver fibrosis.

METHOD

The dataset GSE15654, containing 216 biopsy samples from HCV-induced early-stage cirrhosis patients, was obtained from the GEO database. Prognostic genes were identified through differential gene analysis, LASSO, and Cox regression analyses. CIBERSORT analysis quantified infiltration levels across 22 immune cell types. Constructing a prognostic prediction model using screened genes and conducting preliminary validation using qRT PCR and RNA sequencing techniques.

RESULTS

Elevated SOX9 expression correlates with unfavorable outcomes in patients with early-stage liver fibrosis induced by HCV. We identified nine SOX9-related prognostic DEGs in our study. ADAMTS2, ARHGEF5, CCT8, ERG, LBH, FRMD6, INMT, and RASGRF2 were considered risk factors in the disease progression, while DHRS4 was considered a protective factor. SOX9 expression showed a positive correlation with mast cell infiltration, whereas ARHGEF5 and FRMD6 expressions were positively associated with M0 macrophage infiltration. Our combined model surpasses the commonly used APRI and FIB4 indicators in predicting patient prognosis. The testing of clinical samples also preliminarily validated our research results.

CONCLUSION

The prognostic model based on nine SOX9-related DEGs provides an effective tool for forecasting the progression and outcomes of liver fibrosis. This study introduces a new strategy for advancing liver fibrosis prediction and treatment.

High Shear Stress Reduces ERG Causing Endothelial-Mesenchymal Transition and Pulmonary Arterial Hypertension

BACKGROUND

Computational modeling indicated that pathological high shear stress (HSS; 100 dyn/cm2) is generated in pulmonary arteries (PAs; 100-500 µm) in congenital heart defects causing PA hypertension (PAH) and in idiopathic PAH with occlusive vascular remodeling. Endothelial-to-mesenchymal transition (EndMT) is a feature of PAH. We hypothesize that HSS induces EndMT, contributing to the initiation and progression of PAH.

METHODS

We used the Ibidi perfusion system to determine whether HSS applied to human PA endothelial cells (ECs) induces EndMT when compared with physiological laminar shear stress (15 dyn/cm2). The mechanism was investigated and targeted to prevent PAH in a mouse with HSS induced by an aortocaval shunt.

RESULTS

EndMT, a feature of PAH not previously attributed to HSS, was observed. HSS did not alter the induction of transcription factors KLF (Krüppel-like factor) 2/4, but an ERG (ETS-family transcription factor) was reduced, as were histone H3 lysine 27 acetylation enhancer-promoter peaks containing ERG motifs. Consequently, there was reduced interaction between ERG and KLF2/4, a feature important in tethering KLF and the chromatin remodeling complex to DNA. In PA ECs under laminar shear stress, reducing ERG by siRNA caused EndMT associated with decreased BMPR2 (bone morphogenetic protein receptor 2), CDH5 (cadherin 5), and PECAM1 (platelet and EC adhesion molecule 1) and increased SNAI1/2 (Snail/Slug) and ACTA2 (smooth muscle α2 actin). In PA ECs under HSS, transfection of ERG prevented EndMT. HSS was then induced in mice by an aortocaval shunt, causing progressive PAH over 8 weeks. An adeno-associated viral vector (AAV2-ESGHGYF) was used to replenish ERG selectively in PA ECs. Elevated PA pressure, EndMT, and vascular remodeling (muscularization of peripheral arteries) in the aortocaval shunt mice were markedly reduced by ERG delivery.

CONCLUSIONS

Pathological HSS reduced lung EC ERG, resulting in EndMT and PAH. Agents that upregulate ERG could reverse HSS-mediated PAH and occlusive vascular remodeling resulting from high flow or narrowed PAs.

Microenvironmental determinants of endothelial cell heterogeneity

During development, endothelial cells (ECs) undergo an extraordinary specialization by which generic capillary microcirculatory networks spanning from arteries to veins transform into patterned organotypic zonated blood vessels. These capillary ECs become specialized to support the cellular and metabolic demands of each specific organ, including supplying tissue-specific angiocrine factors that orchestrate organ development, maintenance of organ-specific functions and regeneration of injured adult organs. Here, we illustrate the mechanisms by which microenvironmental signals emanating from non-vascular niche cells induce generic ECs to acquire specific inter-organ and intra-organ functional attributes. We describe how perivascular, parenchymal and immune cells dictate vascular heterogeneity and capillary zonation, and how this system is maintained through tissue-specific signalling activated by vasculogenic and angiogenic factors and deposition of matrix components. We also discuss how perturbation of organotypic vascular niche cues lead to erasure of EC signatures, contributing to the pathogenesis of disease processes. We also describe approaches that use reconstitution of tissue-specific signatures of ECs to promote regeneration of damaged organs.

Targeting endothelial ERG to mitigate vascular regression and neuronal ischemia in retinopathies

Retinopathy of prematurity (ROP) and diabetic retinopathy (DR) are ocular disorders in which a loss of retinal vasculature leads to ischemia followed by a compensatory neovascularization response. In mice, this is modeled using oxygen-induced retinopathy (OIR), whereby neonatal animals are transiently housed under hyperoxic conditions that result in central retina vessel regression and subsequent neovascularization. Using endothelial cell (EC)-specific gene deletion, we found that loss of two ETS-family transcription factors, ERG and FLI1, led to regression of OIR-induced neovascular vessels but failed to improve visual function, suggesting that relevant retinal damage occurs prior to and independently of neovascularization. Turning our attention to the initial stage of OIR, we found that hyperoxia repressed ERG expression in retinal ECs of wild type mice, raising the possibility that oxygen-induced ERG downregulation promotes vessel regression during the initiation of OIR-induced pathology. We therefore developed a murine model of EC-specific ERG overexpression and found it sufficient to prevent hyperoxia-induced vascular regression, neuronal cell death, and neovascularization in the OIR model. Importantly, ERG overexpression also improved visual function in OIR-challenged mice. Moreover, we show that both ERG and FLI1 are downregulated in the retinal vessels of human patients with early stages of DR, suggesting that neovascular disorders of the eye may share common mechanisms underlying pathological retinal capillary regression. Collectively, these data suggest that the regulation of vascular regression by EC-expressed ETS transcription factors may be adapted towards novel therapeutic approaches for the prevention and/or alleviation of ocular neovascular disorders.

Trimethylamine N-oxide promotes PERK-mediated endothelial-mesenchymal transition and apoptosis thereby aggravates atherosclerosis

The endothelial-mesenchymal transition (EndMT) is involved in the development of atherosclerosis (AS) and is a key process in vascular endothelial injury. Oxidative stress, inflammation, and apoptosis are common causes of EndMT, and EndMT progression can further accelerate the development of AS. The metabolite trimethylamine N-oxide (TMAO) is produced by the gut microbiome and is implicated in the development of several diseases, including diabetes and chronic kidney disease. However, the impact of TMAO on transforming growth factor β1(TGF-β1)-induced EndMT remains unclear. We hypothesize that TMAO exacerbates plaque formation and cardiac function impairment by promoting EndMT. Herein, we showed that high serum TMAO levels caused plaque formation, cardiac function damage and haemodynamic changes in ApoE-/- mice. In vitro, TMAO upregulated mesenchymal markers and downregulated endothelial markers in HAECs. Furthermore, TMAO increased the migratory capacity of EndMT cells. Mechanistically, we found that PERK downregulation could alleviate TMAO-induced oxidative stress, EndMT, plaque formation and cardiac function damage. Further study showed that activated transcription factor 3 (ATF3), the downstream molecule of protein kinase RNA-like endoplasmic reticulum kinase (PERK), could bind with TGF-β1/2 and affect EndMT. Overall, TMAO promotes EndMT, possibly through the PERK-eIF2α-ATF4-CHOP or the PERk-eIF2α-ATF3-TGF-β signalling pathways.

Exosomes on the development and progression of renal fibrosis

Renal fibrosis is a prevalent pathological alteration that occurs throughout the progression of primary and secondary renal disorders towards end-stage renal disease. As a complex and irreversible pathophysiological phenomenon, it includes a sequence of intricate regulatory processes at the molecular and cellular levels. Exosomes are a distinct category of extracellular vesicles that play a crucial role in facilitating intercellular communication. Multiple pathways are regulated by exosomes produced by various cell types, including tubular epithelial cells and mesenchymal stem cells, in the context of renal fibrosis. Furthermore, research has shown that exosomes present in bodily fluids, including urine and blood, may be indicators of renal fibrosis. However, the regulatory mechanism of exosomes in renal fibrosis has not been fully elucidated. This article reviewed and analysed the various mechanisms by which exosomes regulate renal fibrosis, which may provide new ideas for further study of the pathophysiological process of renal fibrosis and targeted treatment of renal fibrosis with exosomes.

Angiotensin II depends on hippo/YAP signaling to reprogram angiogenesis and promote liver fibrosis

Liver fibrosis is a chronic pathological process in which the abnormal proliferation of connective tissue is induced by various pathogenic factors. During the process of fibrosis, excessive angiogenesis is observed. Physiological angiogenesis has the potential to impede the progression of liver fibrosis through augmenting matrix metalloenzyme activity; however, pathological angiogenesis can exacerbate liver fibrosis by promoting collagen accumulation. Therefore, a key scientific research focus in the treatment of liver diseases is to search for the "on-off" mechanism that regulates angiogenesis from normal proliferation to pathological proliferation. In this study, we found that excessive angiogenesis appeared during the initial phase of hepatic fibrosis without mesenchymal characteristics. In addition, angiogenesis accompanied by significant endothelial-to-mesenchymal transition (EndMT) was observed in mice after the intraperitoneal injection of angiotensin II (Ang II). Interestingly, the changes in Yes-associated protein (YAP) activity in endothelial cells (ECs) can affect the regulation of angiogenesis by Ang II. The results of in vitro experiments revealed that the regulatory influence of Ang II on ECs was significantly attenuated upon suppression of YAP activity. Furthermore, the function of Ang II in regulating angiogenesis during fibrosis was investigated in liver-specific transgenic mice. The results revealed that Ang II gene deletion could restrain liver fibrosis and EndMT. Meanwhile, Ang II deletion downregulated the profibrotic YAP signaling pathway in ECs. The small molecule AT1R agonist olmesartan targeting Ang II-YAP signaling could also alleviate liver fibrosis. In conclusion, this study identified Ang II as a pivotal regulator of EndMT during the progression of liver fibrosis and evaluated the therapeutic effect of the Ang II-targeted drug olmesartan on liver fibrosis.

Germ line ERG haploinsufficiency defines a new syndrome with cytopenia and hematological malignancy predisposition

ABSTRACT

The genomics era has facilitated the discovery of new genes that predispose individuals to bone marrow failure (BMF) and hematological malignancy (HM). We report the discovery of ETS-related gene (ERG), a novel, autosomal dominant BMF/HM predisposition gene. ERG is a highly constrained transcription factor that is critical for definitive hematopoiesis, stem cell function, and platelet maintenance. ERG colocalizes with other transcription factors, including RUNX family transcription factor 1 (RUNX1) and GATA binding protein 2 (GATA2), on promoters or enhancers of genes that orchestrate hematopoiesis. We identified a rare heterozygous ERG missense variant in 3 individuals with thrombocytopenia from 1 family and 14 additional ERG variants in unrelated individuals with BMF/HM, including 2 de novo cases and 3 truncating variants. Phenotypes associated with pathogenic germ line ERG variants included cytopenias (thrombocytopenia, neutropenia, and pancytopenia) and HMs (acute myeloid leukemia, myelodysplastic syndrome, and acute lymphoblastic leukemia) with onset before 40 years. Twenty ERG variants (19 missense and 1 truncating), including 3 missense population variants, were functionally characterized. Thirteen potentially pathogenic erythroblast transformation specific (ETS) domain missense variants displayed loss-of-function (LOF) characteristics, thereby disrupting transcriptional transactivation, DNA binding, and/or nuclear localization. Selected variants overexpressed in mouse fetal liver cells failed to drive myeloid differentiation and cytokine-independent growth in culture and to promote acute erythroleukemia when transplanted into mice, concordant with these being LOF variants. Four individuals displayed somatic genetic rescue by copy neutral loss of heterozygosity. Identification of predisposing germ line ERG variants has clinical implications for patient and family diagnoses, counseling, surveillance, and treatment strategies, including selection of bone marrow donors and cell or gene therapy.

Stiffness-induced modulation of ERG transcription factor in chronic liver disease

Chronic liver disease (CLD) is characterised by liver sinusoidal endothelial cells (LSECs) dysfunction. Mechanical forces and inflammation are among the leading factors. ETS-related gene (ERG) is an endothelial-specific transcription factor, involved in maintaining cell quiescence and homeostasis. Our study aimed to understand the expression and modulation of ERG in CLD. ERG expression was characterised and correlated to clinical data in human liver cirrhosis at different disease stages. ERG dynamics in response to stiffness and inflammation were investigated in primary healthy and cirrhotic rat LSEC and in human umbilical vein endothelial cells (HUVECs). ERG is markedly downregulated in cirrhosis independently of disease stage or aetiology and its expression is modulated by substrate stiffness in ECs. Inflammation downregulates ERG in cells on physiological stiffness, but not on high stiffness, suggesting a complementary role of inflammation and stiffness in suppressing ERG. This study outlines ERG as an LSEC inflammation and stiffness-responsive transcription factor in cirrhosis.

Differentiation, Metabolism, and Cardioprotective Secretory Functions of Human Cardiac Stromal Cells from Ischemic and Endocarditis Patients

This study investigates the characteristics of cardiac mesenchymal stem cell-like cells (CMSCLCs) isolated from the right atrial appendage of human donors with ischemia and a young patient with endocarditis (NE-CMSCLCs). Typical CMSCLCs from ischemic heart patients were derived from coronary artery bypass grafting procedures and compared against bone marrow mesenchymal stromal cells (BM-MSCs). NE-CMSCLCs had a normal immunophenotype, but exhibited enhanced osteogenic differentiation potential, rapid proliferation, reduced senescence, reduced glycolysis, and lower reactive oxygen species generation after oxidative stress compared with typical ischemic CMSCLCs. These differences suggest a unique functional status of NE-CMSCLCs, influenced by the donor health condition. Despite large variances in their paracrine secretome, NE-CMSCLCs retained therapeutic potential, as indicated by their ability to protect hypoxia/reoxygenation-injured human cardiomyocytes, albeit less effectively than typical CMSCLCs. This research describes a unique cell phenotype and underscores the importance of donor health status in the therapeutic efficacy of autologous cardiac cell therapy.

Integrated single-cell RNA-seq analysis reveals mitochondrial calcium signaling as a modulator of endothelial-to-mesenchymal transition

Endothelial cells (ECs) are highly plastic, capable of differentiating into various cell types. Endothelial-to-mesenchymal transition (EndMT) is crucial during embryonic development and contributes substantially to vascular dysfunction in many cardiovascular diseases (CVDs). While targeting EndMT holds therapeutic promise, understanding its mechanisms and modulating its pathways remain challenging. Using single-cell RNA sequencing on three in vitro EndMT models, we identified conserved gene signatures. We validated original regulators in vitro and in vivo during embryonic heart development and peripheral artery disease. EndMT induction led to global expression changes in all EC subtypes rather than in mesenchymal clusters. We identified mitochondrial calcium uptake as a key driver of EndMT; inhibiting mitochondrial calcium uniporter (MCU) prevented EndMT in vitro, and conditional Mcu deletion in ECs blocked mesenchymal activation in a hind limb ischemia model. Tissues from patients with critical limb ischemia with EndMT features exhibited significantly elevated endothelial MCU. These findings highlight MCU as a regulator of EndMT and a potential therapeutic target.

Pathophysiology in Brain Arteriovenous Malformations: Focus on Endothelial Dysfunctions and Endothelial-to-Mesenchymal Transition

Brain arteriovenous malformations (bAVMs) substantially increase the risk for intracerebral hemorrhage (ICH), which is associated with significant morbidity and mortality. However, the treatment options for bAVMs are severely limited, primarily relying on invasive methods that carry their own risks for intraoperative hemorrhage or even death. Currently, there are no pharmaceutical agents shown to treat this condition, primarily due to a poor understanding of bAVM pathophysiology. For the last decade, bAVM research has made significant advances, including the identification of novel genetic mutations and relevant signaling in bAVM development. However, bAVM pathophysiology is still largely unclear. Further investigation is required to understand the detailed cellular and molecular mechanisms involved, which will enable the development of safer and more effective treatment options. Endothelial cells (ECs), the cells that line the vascular lumen, are integral to the pathogenesis of bAVMs. Understanding the fundamental role of ECs in pathological conditions is crucial to unraveling bAVM pathophysiology. This review focuses on the current knowledge of bAVM-relevant signaling pathways and dysfunctions in ECs, particularly the endothelial-to-mesenchymal transition (EndMT).

Lung injury-induced activated endothelial cell states persist in aging-associated progressive fibrosis

Progressive lung fibrosis is associated with poorly understood aging-related endothelial cell dysfunction. To gain insight into endothelial cell alterations in lung fibrosis we performed single cell RNA-sequencing of bleomycin-injured lungs from young and aged mice. Analysis reveals activated cell states enriched for hypoxia, glycolysis and YAP/TAZ activity in ACKR1+ venous and TrkB+ capillary endothelial cells. Endothelial cell activation is prevalent in lungs of aged mice and can also be detected in human fibrotic lungs. Longitudinal single cell RNA-sequencing combined with lineage tracing demonstrate that endothelial activation resolves in young mouse lungs but persists in aged ones, indicating a failure of the aged vasculature to return to quiescence. Genes associated with activated lung endothelial cells states in vivo can be induced in vitro by activating YAP/TAZ. YAP/TAZ also cooperate with BDNF, a TrkB ligand that is reduced in fibrotic lungs, to promote capillary morphogenesis. These findings offer insights into aging-related lung endothelial cell dysfunction that may contribute to defective lung injury repair and persistent fibrosis.

Large-scale phosphoproteomics reveals activation of the MAPK/GADD45β/P38 axis and cell cycle inhibition in response to BMP9 and BMP10 stimulation in endothelial cells

BACKGROUND

BMP9 and BMP10 are two major regulators of vascular homeostasis. These two ligands bind with high affinity to the endothelial type I kinase receptor ALK1, together with a type II receptor, leading to the direct phosphorylation of the SMAD transcription factors. Apart from this canonical pathway, little is known. Interestingly, mutations in this signaling pathway have been identified in two rare cardiovascular diseases, hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension.

METHODS

To get an overview of the signaling pathways modulated by BMP9 and BMP10 stimulation in endothelial cells, we employed an unbiased phosphoproteomic-based strategy. Identified phosphosites were validated by western blot analysis and regulated targets by RT-qPCR. Cell cycle analysis was analyzed by flow cytometry.

RESULTS

Large-scale phosphoproteomics revealed that BMP9 and BMP10 treatment induced a very similar phosphoproteomic profile. These BMPs activated a non-canonical transcriptional SMAD-dependent MAPK pathway (MEKK4/P38). We were able to validate this signaling pathway and demonstrated that this activation required the expression of the protein GADD45β. In turn, activated P38 phosphorylated the heat shock protein HSP27 and the endocytosis protein Eps15 (EGF receptor pathway substrate), and regulated the expression of specific genes (E-selectin, hyaluronan synthase 2 and cyclooxygenase 2). This study also highlighted the modulation in phosphorylation of proteins involved in transcriptional regulation (phosphorylation of the endothelial transcription factor ERG) and cell cycle inhibition (CDK4/6 pathway). Accordingly, we found that BMP10 induced a G1 cell cycle arrest and inhibited the mRNA expression of E2F2, cyclinD1 and cyclinA1.

CONCLUSIONS

Overall, our phosphoproteomic screen identified numerous proteins whose phosphorylation state is impacted by BMP9 and BMP10 treatment, paving the way for a better understanding of the molecular mechanisms regulated by BMP signaling in vascular diseases.

High Shear Stress Reduces ERG Causing Endothelial-Mesenchymal Transition and Pulmonary Arterial Hypertension

Pathological high shear stress (HSS, 100 dyn/cm 2 ) is generated in distal pulmonary arteries (PA) (100-500 μm) in congenital heart defects and in progressive PA hypertension (PAH) with inward remodeling and luminal narrowing. Human PA endothelial cells (PAEC) were subjected to HSS versus physiologic laminar shear stress (LSS, 15 dyn/cm 2 ). Endothelial-mesenchymal transition (EndMT), a feature of PAH not previously attributed to HSS, was observed. H3K27ac peaks containing motifs for an ETS-family transcription factor (ERG) were reduced, as was ERG-Krüppel-like factors (KLF)2/4 interaction and ERG expression. Reducing ERG by siRNA in PAEC during LSS caused EndMT; transfection of ERG in PAEC under HSS prevented EndMT. An aorto-caval shunt was preformed in mice to induce HSS and progressive PAH. Elevated PA pressure, EndMT and vascular remodeling were reduced by an adeno-associated vector that selectively replenished ERG in PAEC. Agents maintaining ERG in PAEC should overcome the adverse effect of HSS on progressive PAH.

Liver endothelial cells in NAFLD and transition to NASH and HCC

Non-alcoholic fatty liver disease (NAFLD) is considered as the hepatic manifestation of metabolic syndrome, which is characterised by obesity, insulin resistance, hypercholesterolemia and hypertension. NAFLD is the most frequent liver disease worldwide and more than 10% of NAFLD patients progress to the inflammatory and fibrotic stage of non-alcoholic steatohepatitis (NASH), which can lead to end-stage liver disease including hepatocellular carcinoma (HCC), the most frequent primary malignant liver tumor. Liver sinusoidal endothelial cells (LSEC) are strategically positioned at the interface between blood and hepatic parenchyma. LSECs are highly specialized cells, characterised by the presence of transcellular pores, called fenestrae, and exhibit anti-inflammatory and anti-fibrotic characteristics under physiological conditions. However, during NAFLD development they undergo capillarisation and acquire a phenotype similar to vascular endothelial cells, actively promoting all pathophysiological aspects of NAFLD, including steatosis, inflammation, and fibrosis. LSEC dysfunction is critical for the progression to NASH and HCC while restoring LSEC homeostasis appears to be a promising approach to prevent NAFLD progression and its complications and even reverse tissue damage. In this review we present current information on the role of LSEC throughout the progressive phases of NAFLD, summarising in vitro and in vivo experimental evidence and data from human studies.

Bmp9 regulates Notch signaling and the temporal dynamics of angiogenesis via Lunatic Fringe

In brief

The mechanisms regulating the signaling pathways involved in angiogenesis are not fully known. Ristori et al. show that Lunatic Fringe (LFng) mediates the crosstalk between Bone Morphogenic Protein 9 (Bmp9) and Notch signaling, thereby regulating the endothelial cell behavior and temporal dynamics of their identity during sprouting angiogenesis.

Highlights

Bmp9 upregulates the expression of LFng in endothelial cells.LFng regulates the temporal dynamics of tip/stalk selection and rearrangement.LFng indicated to play a role in hereditary hemorrhagic telangiectasia.Bmp9 and LFng mediate the endothelial cell-pericyte crosstalk.Bone Morphogenic Protein 9 (Bmp9), whose signaling through Activin receptor-like kinase 1 (Alk1) is involved in several diseases, has been shown to independently activate Notch target genes in an additive fashion with canonical Notch signaling. Here, by integrating predictive computational modeling validated with experiments, we uncover that Bmp9 upregulates Lunatic Fringe (LFng) in endothelial cells (ECs), and thereby also regulates Notch activity in an inter-dependent, multiplicative fashion. Specifically, the Bmp9-upregulated LFng enhances Notch receptor activity creating a much stronger effect when Dll4 ligands are also present. During sprouting, this LFng regulation alters vessel branching by modulating the timing of EC phenotype selection and rearrangement. Our results further indicate that LFng can play a role in Bmp9-related diseases and in pericyte-driven vessel stabilization, since we find LFng contributes to Jag1 upregulation in Bmp9-stimulated ECs; thus, Bmp9-upregulated LFng results in not only enhanced EC Dll4-Notch1 activation, but also Jag1-Notch3 activation in pericytes.

Cx43 Facilitates Mesenchymal Transition of Endothelial Cells Induced by Shear Stress

OBJECTIVES

This study aimed to determine the function of Cx43 in the endothelial-to-mesenchymal transition (EndMT) process of endothelial cells (ECs) and to explore the potential signaling pathways underlying these functions.

METHODS

ECs were extracted from rat aorta. ECs were transfected with Cx43 cDNA and Cx43 siRNA and then exposed to 5 or 12 dyne/cm2. Immunofluorescence staining was used to detect the expression of SM22α, Cx43, and acetylated α-tubulin in ECs. Western blotting was used to detect the protein expression of α-SMA, CD31, Cx43, H1-calponin, Ift88, and p-smad3 in ECs.

RESULTS

The expression of αSMA, SM22α, and Cx43 was significantly increased, and CD31 was markedly decreased in ECs treated with laminar shear stress at 5 dyn/cm2. The Cx43 cDNA transfection could induce the expression of SM22α or H1-calponin and attenuate CD31 expression in ECs. Also, Cx43 overexpression harms cilia formation in ECs exposed to 5 dyn/cm2, accompanied with the regulated Ift88 and smad signaling.

CONCLUSIONS

This study found that laminar shear stress at 5 dyn/cm2 would increase the expression of Cx43 to facilitate the EndMT process of ECs, associated with morphological changes in primary cilia and the decreased expression of Ift88 in ECs.

Vascular Contribution to Lung Repair and Fibrosis

Lungs are constantly exposed to environmental perturbations and therefore have remarkable capacity to regenerate in response to injury. Sustained lung injuries, aging, and increased genomic instability, however, make lungs particularly susceptible to disrepair and fibrosis. Pulmonary fibrosis constitutes a major cause of morbidity and is often relentlessly progressive, leading to death from respiratory failure. The pulmonary vasculature, which is critical for gas exchanges and plays a key role during lung development, repair, and regeneration, becomes aberrantly remodeled in patients with progressive pulmonary fibrosis. Although capillary rarefaction and increased vascular permeability are recognized as distinctive features of fibrotic lungs, the role of vasculature dysfunction in the pathogenesis of pulmonary fibrosis has only recently emerged as an important contributor to the progression of this disease. This review summarizes current findings related to lung vascular repair and regeneration and provides recent insights into the vascular abnormalities associated with the development of persistent lung fibrosis.

Dihydroergotamine ameliorates liver fibrosis by targeting transforming growth factor β type II receptor

BACKGROUND

The transforming growth factor β (TGFβ) signaling pathway plays a crucial role in the development of liver fibrosis by activating TGFβ type II receptor (TGFβR2), followed by the recruitment of TGFβR1 finally triggering downstream signaling pathway.

AIM

To find drugs targeting TGFβR2 that inhibit TGFβR1/TGFβR2 complex formation, theoretically inhibit TGFβ signaling pathway, and thereby ameliorate liver fibrosis.

METHODS

Food and Drug Administration-approved drugs were screened for binding affinity with TGFβR2 by virtual molecular docking. We identified 6 candidates and further explored their potential by Cell Counting Kit-8 (CCK-8) cell cytotoxic experiment to validate toxicity and titrated the best cellular working concentrations. Next, we further demonstrated the detailed molecular working mechanisms using mutagenesis analysis. Finally, we used a mouse model to investigate its potential anti-liver fibrosis effect.

RESULTS

We identified 6 drug candidates. Among these 6 drugs, dihydroergotamine (DHE) shows great ability in reducing fibrotic gene expressions such as collagen, p-SMAD3, and α-SMA in TGFβ induced cellular model of liver fibrosis in LX-2 cells. Furthermore, we demonstrated that DHE binds to TGFβR2. Moreover, mutation of Leu27, Phe30, Thr51, Ser52, Ile53, and Glu55 of TGFβR2 disrupted the binding of TGFβR2 with DHE. In addition, DHE significantly improved liver fibrosis, as evidenced by Masson’s trichrome staining of liver sections. This is further supported by the width and the velocity of the portal vein, and serum markers of liver function. In line with those observations, DHE also decreased macrophages infiltration and extracellular matrix deposition in the liver.

CONCLUSION

DHE alleviates liver fibrosis by binding to TGFβR2 thereby suppressing TGFβ signaling pathway. We show here that as far as drug repurposing, DHE has great potential to treat liver fibrosis.

The tissue-specific transcriptional landscape underlines the involvement of endothelial cells in health and disease

Endothelial cells (ECs) that line vascular and lymphatic vessels are being increasingly recognized as important to organ function in health and disease. ECs participate not only in the trafficking of gases, metabolites, and cells between the bloodstream and tissues but also in the angiocrine-based induction of heterogeneous parenchymal cells, which are unique to their specific tissue functions. The molecular mechanisms regulating EC heterogeneity between and within different tissues are modeled during embryogenesis and become fully established in adults. Any changes in adult tissue homeostasis induced by aging, stress conditions, and various noxae may reshape EC heterogeneity and induce specific transcriptional features that condition a functional phenotype. Heterogeneity is sustained via specific genetic programs organized through the combinatory effects of a discrete number of transcription factors (TFs) that, at the single tissue-level, constitute dynamic networks that are post-transcriptionally and epigenetically regulated. This review is focused on outlining the TF-based networks involved in EC specialization and physiological and pathological stressors thought to modify their architecture.

Sulodexide attenuates liver fibrosis in mice by restoration of differentiated liver sinusoidal endothelial cell

Sulodexide is a heparinoid compound with wide-ranging pharmacological activities. However, the effect of sulodexide on liver fibrogenesis has not been reported. In this study, we aim to evaluate the therapeutic potential of sulodexide in mouse model of liver fibrosis and explore the underlying antifibrotic mechanisms. We found that sulodexide treatment significantly attenuated thioacetamide (TAA) and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced liver fibrosis in mice. Transcriptome analysis revealed that sulodexide treatment downregulated fibrosis-related genes and liver sinusoidal endothelial cells (LSECs) capillarization-associated genes in fibrotic livers. Immunohistochemistry confirmed that the increased expression of LSEC capillarization-related genes (CD34, CD31 and Laminin) in liver fibrotic tissues was reduced by sulodexide treatment. Scanning electron microscopy showed that LSECs fenestrations were preserved upon sulodexide treatment. Quantitative real-time PCR and immunofluorescence demonstrated that the expression of mesenchymal markers was downregulated by sulodexide administration, suggesting sulodexide inhibited endothelial-mesenchymal transition of LSECs during liver fibrosis. Furthermore, sulodexide administration protected primary LSECs from endothelial dysfunction in vitro. In conclusion, sulodexide attenuated liver fibrosis in mice by restoration of differentiated LSECs, indicating that sulodexide treatment may present as a potential therapy for patients with liver fibrosis.

The roles of ETS transcription factors in liver fibrosis

E26 transformation specific or E twenty-six (ETS) protein family consists of 28 transcription factors, five of which, named ETS1/2, PU.1, ERG and EHF, are known to involve in the development of liver fibrosis, and are expected to become diagnostic markers or therapeutic targets of liver fibrosis. In recent years, some small molecule inhibitors of ETS protein family have been discovered, which might open up a new path for the liver fibrosis therapy targeting ETS. This article reviews the research progress of ETS family members in the development liver fibrosis as well as their prospect of clinical application.

Cytokine-Mediated Degradation of the Transcription Factor ERG Impacts the Pulmonary Vascular Response to Systemic Inflammatory Challenge

Background

During infectious diseases, pro-inflammatory cytokines transiently destabilize interactions between adjacent vascular endothelial cells (ECs) to facilitate the passage of immune molecules and cells into tissues. However, in the lung the resulting vascular hyperpermeability can lead to organ dysfunction. Previous work identified the transcription factor ERG as a master regulator of endothelial homeostasis. Here we investigate whether the sensitivity of pulmonary blood vessels to cytokine-induced destabilization is due to organotypic mechanisms affecting the ability of endothelial ERG to protect lung ECs from inflammatory injury.

Methods

Cytokine-dependent ubiquitination and proteasomal degradation of ERG was analyzed in cultured Human Umbilical Vein ECs (HUVECs). Systemic administration of TNFα or the bacterial cell wall component lipopolysaccharide (LPS) was used to cause a widespread inflammatory challenge in mice; ERG protein levels were assessed by immunoprecipitation, immunoblot, and immunofluorescence. Murine Erg deletion was genetically induced in ECs ( Erg fl/fl ;Cdh5(PAC)Cre ERT2 ), and multiple organs were analyzed by histology, immunostaining, and electron microscopy.

Results

In vitro, TNFα promoted the ubiquitination and degradation of ERG in HUVECs, which was blocked by the proteasomal inhibitor MG132. In vivo, systemic administration of TNFα or LPS resulted in a rapid and substantial degradation of ERG within lung ECs, but not ECs of the retina, heart, liver, or kidney. Pulmonary ERG was also downregulated in a murine model of influenza infection. Erg fl/fl ;Cdh5(PAC)-Cre ERT2 mice spontaneously recapitulated aspects of inflammatory challenges, including lung-predominant vascular hyperpermeability, immune cell recruitment, and fibrosis. These phenotypes were associated with a lung-specific decrease in the expression of Tek , a gene target of ERG previously implicated in maintaining pulmonary vascular stability during inflammation.

Conclusions

Collectively, our data highlight a unique role for ERG in pulmonary vascular function. We propose that cytokine-induced ERG degradation and subsequent transcriptional changes in lung ECs play critical roles in the destabilization of pulmonary blood vessels during infectious diseases.

Cooperative ETS Transcription Factors Enforce Adult Endothelial Cell Fate and Cardiovascular Homeostasis

Current dogma dictates that during adulthood, endothelial cells (ECs) are locked in an immutable stable homeostatic state. By contrast, herein we show that maintenance of EC fate and function are linked and active processes, which depend on the constitutive cooperativity of only two ETS-transcription factors (TFs) ERG and Fli1. While deletion of either Fli1 or ERG manifest subtle vascular dysfunction, their combined genetic deletion in adult EC results in acute vasculopathy and multiorgan failure, due to loss of EC fate and integrity, hyperinflammation, and spontaneous thrombosis, leading to death. ERG and Fli1 co-deficiency cause rapid transcriptional silencing of pan- and organotypic vascular core genes, with dysregulation of inflammation and coagulation pathways. Vascular hyperinflammation leads to impaired hematopoiesis with myeloid skewing. Accordingly, enforced ERG and FLI1 expression in adult human mesenchymal stromal cells activates vascular programs and functionality enabling engraftment of perfusable vascular network. GWAS-analysis identified vascular diseases are associated with FLI1/Erg mutations. Constitutive expression of ERG and Fli1 uphold EC fate, physiological function, and resilience in adult vasculature; while their functional loss can contribute to systemic human diseases.

Novel application of live imaging to determine the functional cell biology of endothelial-to-mesenchymal transition (EndMT) within a liver-on-a-chip platform

Objective

Imaging endothelial cell behaviour under physiological conditions, particularly those associated with chronic fibrotic pathologies, is an incredibly challenging endeavour. While short-term assessments (hours) can be achieved with techniques such as intravital microscopy, vascular changes often occur over days and weeks which is unfeasible with current imaging techniques. These challenges are exemplified within the liver where liver sinusoidal endothelial cells (LSECs) are known to undergo dramatic changes termed endothelial-to-mesenchymal transition (EndMT) during fibrotic liver disease. Despite the established presence of EndMT in liver disease, the inaccessibility of viable liver tissue, and simplicity of 2D culture techniques has meant, the role of EndMT during disease progression remains largely undetermined. This study describes the development of novel fluorescent EndMT reporters to identify, track, and characterise the migratory behaviour of EndMT cells. We show that liver-on-a-chip (LOAC) platforms provide a flexible, optically accessible, and physiologically relevant microenvironment to study the vascular dynamics of EndMT during liver disease.

Methods

Identification, creation, and application of an EndMT-specific fluorescent reporter construct (EndMT-Rep). Transduction of EC using lentiviral packaged CNN1-eGFP construct as an inducible EndMT-Rep (CNN1-Rep) to 2D, 3D, and 4D imaging techniques for fixed and live cell imaging. Combined application of live and fixed imaging technologies to measure EndMT using CNN1-Rep on LOAC platform under physiological conditions. Demonstration of the high-resolution single-cell EndMT tracking by live cell time-lapse microscopy and with post-acquisition processing to perform a comparative study of CNN1-Rep and healthy LSECs within a NASH-like LOAC microenvironment.

Conclusions

LOAC enables prolonged, multi-platform imaging of endothelial cell sub-populations such as those undergoing EndMT in 2D and 3D cultures. Our study highlights the application of EndMT reporters, such as CNN1-Rep, to provide high-resolution imaging of EndMT behaviour for the first time under physiologically relevant liver microenvironment. Overall, these methods reveal the adaptability and impact of live-cell imaging on uncovering vascular behaviours, such as EndMT, that are unattainable in viable tissue or conventional 2D in vitro experiments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s44164-022-00034-9.

The Endothelial Transcription Factor ERG Mediates a Differential Role in the Aneurysmatic Ascending Aorta with Bicuspid or Tricuspid Aorta Valve: A Preliminary Study

The pathobiology of ascending aorta aneurysms (AAA) onset and progression is not well understood and only partially characterized. AAA are also complicated in case of bicuspid aorta valve (BAV) anatomy. There is emerging evidence about the crucial role of endothelium-related pathways, which show in AAA an altered expression and function. Here, we examined the involvement of ERG-related pathways in the differential progression of disease in aortic tissues from patients having a BAV or tricuspid aorta valve (TAV) with or without AAA. Our findings identified ERG as a novel endothelial-specific regulator of TGF-β-SMAD, Notch, and NO pathways, by modulating a differential fibrotic or calcified AAA progression in BAV and TAV aortas. We provided evidence that calcification is correlated to different ERG expression (as gene and protein), which appears to be under control of Notch signaling. The latter, when increased, associated with an early calcification in aortas with BAV valve and aneurysmatic, was demonstrated to favor the progression versus severe complications, i.e., dissection or rupture. In TAV aneurysmatic aortas, ERG appeared to modulate fibrosis. Therefore, we proposed that ERG may represent a sensitive tissue biomarker to monitor AAA progression and a target to develop therapeutic strategies and influence surgical procedures.

Trophism and Homeostasis of Liver Sinusoidal Endothelial Graft Cells during Preservation, with and without Hypothermic Oxygenated Perfusion

The aim of the present study was to evaluate the homeostasis and trophism of liver sinusoidal endothelial cells (LSECs) in vivo in different stages of liver graft donation, in order to understand the effects of graft ischemia and perfusion on LSEC activity in liver grafts. Special attention was paid to grafts that underwent hypothermic oxygenated perfusion (HOPE). Forty-seven donors were prospectively enrolled, and two distinct biopsies were performed in each case: one allocation biopsy (at the stage of organ allocation) and one post-perfusion biopsy, performed after graft implant in the recipients. In all biopsies, immunohistochemistry and RT-PCR analyses were carried out for the endothelial markers CD34, ERG, Nestin, and VEGFR-2. We observed an increase in CD34 immunoreactivity in LSEC during the whole preservation/perfusion period (p < 0.001). Nestin and ERG expression was low in allocation biopsies, but increased in post-perfusion biopsies, in both immunohistochemistry and RT-PCR (p < 0.001). An inverse correlation was observed between ERG positivity and donor age. Our results indicate that LSEC trophism is severely depressed in liver grafts, but it is restored after reperfusion in standard conditions. The execution of HOPE seems to improve this recovery, confirming the effectiveness of this machine perfusion technique in restoring endothelial functions.

Dysfunctional ERG signaling drives pulmonary vascular aging and persistent fibrosis

Vascular dysfunction is a hallmark of chronic diseases in elderly. The contribution of the vasculature to lung repair and fibrosis is not fully understood. Here, we performed an epigenetic and transcriptional analysis of lung endothelial cells (ECs) from young and aged mice during the resolution or progression of bleomycin-induced lung fibrosis. We identified the transcription factor ETS-related gene (ERG) as putative orchestrator of lung capillary homeostasis and repair, and whose function is dysregulated in aging. ERG dysregulation is associated with reduced chromatin accessibility and maladaptive transcriptional responses to injury. Loss of endothelial ERG enhances paracrine fibroblast activation in vitro, and impairs lung fibrosis resolution in young mice in vivo. scRNA-seq of ERG deficient mouse lungs reveales transcriptional and fibrogenic abnormalities resembling those associated with aging and human lung fibrosis, including reduced number of general capillary (gCap) ECs. Our findings demonstrate that lung endothelial chromatin remodeling deteriorates with aging leading to abnormal transcription, vascular dysrepair, and persistent fibrosis following injury.

HMGB1 induced endothelial to mesenchymal transition in liver fibrosis: The key regulation of early growth response factor 1

BACKGROUND

Liver fibrosis has been the focus and difficulty of medical research in the world and its concrete pathogenesis remains unclear. This study aims to observe the high-mobility group box 1 (HMGB1)-induced hepatic endothelial to mesenchymal transition (EndoMT) during the development of hepatic fibrosis, and further to explore the crucial involvement of Egr1 in this process.

METHODS

Carbon tetrachloride (CCl₄), diosbulbin B (DB), N-acetyl-p-aminophenol (APAP) and bile duct ligation (BDL) were used to induce liver fibrosis in mice. Serum HMGB1 content, the occurrence of EndoMT and the production of extracellular matrix (ECM) in vitro and in vivo were detected by Western-blot.

RESULTS

The elevated serum HMGB1 content, the occurrence of EndoMT, the production of ECM and the activation of Egr1 were observed in mice with liver fibrosis induced by CCl₄, DB, APAP or BDL. HMGB1 induced EndoMT and ECM production in human hepatic sinusoidal endothelial cells (HHSECs), and then HHSECs lost the ability to inhibit the activation of hepatic stellate cells (HSCs). The hepatic deposition of collagen, the increased serum HMGB1 content and hepatic EndoMT were further aggravated in Egr1 knockout mice. Natural compound silymarin attenuated liver fibrosis in mice induced by CCl₄ via increasing Egr1 nuclear accumulation, decreasing serum HMGB1 content and inhibiting hepatic EndoMT.

CONCLUSION

Egr1 regulated the expression of HMGB1 that induced hepatic EndoMT, which plays an important role in the development of liver fibrosis.

GENERAL SIGNIFICANCE

This study provides a novel therapeutic strategy for the treatment of liver fibrosis in clinic.

ERG activity is regulated by endothelial FAK coupling with TRIM25/USP9x in vascular patterning

Precise vascular patterning is crucial for normal growth and development. The ERG transcription factor drives Delta-like ligand 4 (DLL4)/Notch signalling and is thought to act as a pivotal regulator of endothelial cell (EC) dynamics and developmental angiogenesis. However, molecular regulation of ERG activity remains obscure. Using a series of EC-specific focal adhesion kinase (FAK)-knockout (KO) and point-mutant FAK-knock-in mice, we show that loss of ECFAK, its kinase activity or phosphorylation at FAK-Y397, but not FAK-Y861, reduces ERG and DLL4 expression levels together with concomitant aberrations in vascular patterning. Rapid immunoprecipitation mass spectrometry of endogenous proteins identified that endothelial nuclear-FAK interacts with the deubiquitinase USP9x and the ubiquitin ligase TRIM25. Further in silico analysis confirms that ERG interacts with USP9x and TRIM25. Moreover, ERG levels are reduced in FAKKO ECs via a ubiquitin-mediated post-translational modification programme involving USP9x and TRIM25. Re-expression of ERG in vivo and in vitro rescues the aberrant vessel-sprouting defects observed in the absence of ECFAK. Our findings identify ECFAK as a regulator of retinal vascular patterning by controlling ERG protein degradation via TRIM25/USP9x.

Halawa T, Ahmed Wani ِF. Epigallocatechin gallate ameliorates tetrahydrochloride-induced liver toxicity in rats via inhibition of TGFβ / p-ERK/p-Smad1/2 signaling, antioxidant, anti-inflammatory activity

Chronic liver disease is a worldwide health problem. Carbon tetra hydrochloride is an environmental toxin which is regarded as highly toxic and a potential human carcinogen. It can cause liver damage through the generation of metabolites and production of free radicals. Green tea contains catechins such as Epigallocatechin gallate which has been found to reduce the inflammation, oxidative stress, and fibrosis in experimental animal models. Hence, it represents a good source to prevent or ameliorate several chronic diseases. Silymarin is extracted from milk thistle seeds and has been found to be an effective agent to reduce the oxidative stress and free radical production and thereby exert protective effects in chronic liver conditions. The present study was planned to keep in view the above-mentioned facts. We included thirty rats in our study and divided them into five groups, each having six rats and the study continued for 8 weeks. Group I received normal saline; Group 2 received i.p. CCl4 injections; Group 3 received CCl4 i.p. injection and Epigallocatechin gallate (EGCG) oral gavage, Group 4 received CCl4 i.p. injection and silymarin by oral gavage; and Group 5 received CCl4 i.p. injection and combined EGCG + silymarin by oral gavage. The study found that in group 2, CCl4 induced significant elevation of ALT and MDA and reduced GSH thereby signifying increased oxidative stress. CCl4 also significantly increased inflammatory (TNFα, NFκB, IL1β, and TGFβ) as well as fibrotic markers (p-ERK and p-Smad1/2 protein expression). EGCG and silymarin significantly reversed the previously mentioned parameters either alone or in combination; however, the effect was more pronounced in case of EGCG. We conclude that EGCG and silymarin possess liver protective effects through their antioxidant, anti-inflammatory, and antifibrotic action.

The Evolution of Biomineralization through the Co-Option of Organic Scaffold Forming Networks

Biomineralization is the process in which organisms use minerals to generate hard structures like teeth, skeletons and shells. Biomineralization is proposed to have evolved independently in different phyla through the co-option of pre-existing developmental programs. Comparing the gene regulatory networks (GRNs) that drive biomineralization in different species could illuminate the molecular evolution of biomineralization. Skeletogenesis in the sea urchin embryo was extensively studied and the underlying GRN shows high conservation within echinoderms, larval and adult skeletogenesis. The organic scaffold in which the calcite skeletal elements form in echinoderms is a tubular compartment generated by the syncytial skeletogenic cells. This is strictly different than the organic cartilaginous scaffold that vertebrates mineralize with hydroxyapatite to make their bones. Here I compare the GRNs that drive biomineralization and tubulogenesis in echinoderms and in vertebrates. The GRN that drives skeletogenesis in the sea urchin embryo shows little similarity to the GRN that drives bone formation and high resemblance to the GRN that drives vertebrates’ vascular tubulogenesis. On the other hand, vertebrates’ bone-GRNs show high similarity to the GRNs that operate in the cells that generate the cartilage-like tissues of basal chordate and invertebrates that do not produce mineralized tissue. These comparisons suggest that biomineralization in deuterostomes evolved through the phylum specific co-option of GRNs that control distinct organic scaffolds to mineralization.

Emerging roles of inflammation-mediated endothelial–mesenchymal transition in health and disease

Endothelial–mesenchymal transition (EndoMT), a cellular differentiation process in which endothelial cells (ECs) lose their properties and differentiate into mesenchymal cells, has been observed not only during development but also in various pathological states in adults, including cancer progression and organ/tissue fibrosis. Transforming growth factor-β (TGF-β), an inflammation-related cytokine, has been shown to play central roles in the induction of EndoMT. TGF-β induces EndoMT by regulating the expression of various transcription factors, signaling molecules, and cellular components that confer ECs with mesenchymal characteristics. However, TGF-β by itself is not necessarily sufficient to induce EndoMT to promote the progression of EndoMT-related diseases to a refractory extent. In addition to TGF-β, additional activation by other inflammatory factors is often required to stabilize the progression of EndoMT. Since recent lines of evidence indicate that inflammatory signaling molecules act as enhancers of EndoMT, we summarize the roles of inflammatory factors in the induction of EndoMT and related diseases. We hope that this review will help to develop therapeutic strategies for EndoMT-related diseases by targeting inflammation-mediated EndoMT.

Combination Therapy of Placenta-Derived Mesenchymal Stem Cells with WKYMVm Promotes Hepatic Function in a Rat Model with Hepatic Disease via Vascular Remodeling

Changes in the structure and function of blood vessels are important factors that play a primary role in regeneration of injured organs. WKYMVm has been reported as a therapeutic factor that promotes the migration and proliferation of angiogenic cells. Additionally, we previously demonstrated that placenta-derived mesenchymal stem cells (PD-MSCs) induce hepatic regeneration in hepatic failure via antifibrotic effects. Therefore, our objectives were to analyze the combination effect of PD-MSCs and WKYMVm in a rat model with bile duct ligation (BDL) and evaluate their therapeutic mechanism. To analyze the anti-fibrotic and angiogenic effects on liver regeneration, it was analyzed using ELISA, qRT-PCR, Western blot, immunofluorescence, and immunohistochemistry. Collagen accumulation was significantly decreased in PD-MSCs with the WKYMVm combination (Tx+WK) group compared with the nontransplantation (NTx) and PD-MSC-transplanted (Tx) group (p < 0.05). Furthermore, the combination of PD-MSCs with WKYMVm significantly promoted hepatic function by increasing hepatocyte proliferation and albumin as well as angiogenesis by activated FPR2 signaling (p < 0.05). The combination therapy of PD-MSCs with WKYMVm could be an efficient treatment in hepatic diseases via vascular remodeling. Therefore, the combination therapy of PD-MSCs with WKYMVm could be a new therapeutic strategy in degenerative medicine.

Group Young Researchers in Inflammatory Carcinogenesis, Wandmacher AM, Mehdorn AS, Sebens S. The Heterogeneity of the Tumor Microenvironment as Essential Determinant of Development, Progression and Therapy Response of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is commonly diagnosed at advanced stages and most anti-cancer therapies have failed to substantially improve prognosis of PDAC patients. As a result, PDAC is still one of the deadliest tumors. Tumor heterogeneity, manifesting at multiple levels, provides a conclusive explanation for divergent survival times and therapy responses of PDAC patients. Besides tumor cell heterogeneity, PDAC is characterized by a pronounced inflammatory stroma comprising various non-neoplastic cells such as myofibroblasts, endothelial cells and different leukocyte populations which enrich in the tumor microenvironment (TME) during pancreatic tumorigenesis. Thus, the stromal compartment also displays a high temporal and spatial heterogeneity accounting for diverse effects on the development, progression and therapy responses of PDAC. Adding to this heterogeneity and the impact of the TME, the microbiome of PDAC patients is considerably altered. Understanding this multi-level heterogeneity and considering it for the development of novel therapeutic concepts might finally improve the dismal situation of PDAC patients. Here, we outline the current knowledge on PDAC cell heterogeneity focusing on different stromal cell populations and outline their impact on PDAC progression and therapy resistance. Based on this information, we propose some novel concepts for treatment of PDAC patients.

Endothelial-Mesenchymal Transition in Cardiovascular Disease

Endothelial-to-mesenchymal transition is a dynamic process in which endothelial cells suppress constituent endothelial properties and take on mesenchymal cell behaviors. To begin the process, endothelial cells loosen their cell-cell junctions, degrade the basement membrane, and migrate out into the perivascular surroundings. These initial endothelial behaviors reflect a transient modulation of cellular phenotype, that is, a phenotypic modulation, that is sometimes referred to as partial endothelial-to-mesenchymal transition. Loosening of endothelial junctions and migration are also seen in inflammatory and angiogenic settings such that endothelial cells initiating endothelial-to-mesenchymal transition have overlapping behaviors and gene expression with endothelial cells responding to inflammatory signals or sprouting to form new blood vessels. Reduced endothelial junctions increase permeability, which facilitates leukocyte trafficking, whereas endothelial migration precedes angiogenic sprouting and neovascularization; both endothelial barriers and quiescence are restored as inflammatory and angiogenic stimuli subside. Complete endothelial-to-mesenchymal transition proceeds beyond phenotypic modulation such that mesenchymal characteristics become prominent and endothelial functions diminish. In proadaptive, regenerative settings the new mesenchymal cells produce extracellular matrix and contribute to tissue integrity whereas in maladaptive, pathologic settings the new mesenchymal cells become fibrotic, overproducing matrix to cause tissue stiffness, which eventually impacts function. Here we will review what is known about how TGF (transforming growth factor) β influences this continuum from junctional loosening to cellular migration and its relevance to cardiovascular diseases.

Persistent RNA virus infection is short-lived at the single-cell level but leaves transcriptomic footprints

Several RNA viruses can establish life-long persistent infection in mammalian hosts, but the fate of individual virus-infected cells remains undefined. Here we used Cre recombinase-encoding lymphocytic choriomeningitis virus to establish persistent infection in fluorescent cell fate reporter mice. Virus-infected hepatocytes underwent spontaneous noncytolytic viral clearance independently of type I or type II interferon signaling or adaptive immunity. Viral clearance was accompanied by persistent transcriptomic footprints related to proliferation and extracellular matrix remodeling, immune responses, and metabolism. Substantial overlap with persistent epigenetic alterations in HCV-cured patients suggested a universal RNA virus-induced transcriptomic footprint. Cell-intrinsic clearance occurred in cell culture, too, with sequential infection, reinfection cycles separated by a period of relative refractoriness to infection. Our study reveals that systemic persistence of a prototypic noncytolytic RNA virus depends on continuous spread and reinfection. Yet undefined cell-intrinsic mechanisms prevent viral persistence at the single-cell level but give way to profound transcriptomic alterations in virus-cleared cells.

Capillarized Liver Sinusoidal Endothelial Cells Undergo Partial Endothelial-Mesenchymal Transition to Actively Deposit Sinusoidal ECM in Liver Fibrosis

Tissue-specific endothelial cells are more than simply a barrier lining capillaries and are proved to be capable of remarkable plasticity to become active collagen matrix-producing myofibroblasts (MFs) in solid organs with fibrosis. Liver sinusoidal endothelial cells (LSECs) also participate in the development of hepatic fibrosis, but the exact roles and underlying mechanism have been poorly understood in addition to capillarization. In this study, we demonstrate, by using single-cell RNA sequencing, lineage tracing, and colocalization analysis, that fibrotic LSECs undergo partial endothelial mesenchymal transition (EndMT) with a subset of LSECs acquiring an MF-like phenotype. These phenotypic changes make LSECs substantial producers of extracellular matrix (ECM) preferentially deposited in liver sinusoids but not septal/portal scars as demonstrated by immunofluorescence in animal models and patients with fibrosis/cirrhosis, likely due to their limited migration. Bioinformatic analysis verifies that LSECs undergo successive phenotypic transitions from capillarization to mesenchymal-like cells in liver fibrosis. Furthermore, blockade of LSEC capillarization by using YC-1, a selective eNOS-sGC activator, effectively attenuates liver damage and fibrogenesis as well as mesenchymal features of LSECs, suggesting that capillarization of LSECs might be upstream to their mesenchymal transition during fibrosis. In conclusion, we report that capillarized LSECs undergo a partial EndMT characterized by increased ECM production without activating cell mobility, leading to perisinusoidal ECM deposition that aggravate liver function and fibrogenesis. Targeting this transitional process may be of great value for antifibrotic treatment of liver fibrosis.

Identification of hepatic fibrosis inhibitors through morphometry analysis of a hepatic multicellular spheroids model

A chronic, local inflammatory milieu can cause tissue fibrosis that results in epithelial-to-mesenchymal transition (EMT), endothelial-to-mesenchymal transition (EndMT), increased abundance of fibroblasts, and further acceleration of fibrosis. In this study, we aimed to identify potential mechanisms and inhibitors of fibrosis using 3D model-based phenotypic screening. We established liver fibrosis models using multicellular tumor spheroids (MCTSs) composed of hepatocellular carcinoma (HCC) and stromal cells such as fibroblasts (WI38), hepatic stellate cells (LX2), and endothelial cells (HUVEC) seeded at constant ratios. Through high-throughput screening of FDA-approved drugs, we identified retinoic acid and forskolin as candidates to attenuate the compactness of MCTSs as well as inhibit the expression of ECM-related proteins. Additionally, retinoic acid and forskolin induced reprogramming of fibroblast and cancer stem cells in the HCC microenvironment. Of interest, retinoic acid and forskolin had anti-fibrosis effects by decreasing expression of α-SMA and F-actin in LX2 cells and HUVEC cells. Moreover, when sorafenib was added along with retinoic acid and forskolin, apoptosis was increased, suggesting that anti-fibrosis drugs may improve tissue penetration to support the efficacy of anti-cancer drugs. Collectively, these findings support the potential utility of morphometric analyses of hepatic multicellular spheroid models in the development of new drugs with novel mechanisms for the treatment of hepatic fibrosis and HCCs.

Evidence for synergy between sarcomeres and fibroblasts in an in vitro model of myocardial reverse remodeling

We have created a novel in-vitro platform to study reverse remodeling of engineered heart tissue (EHT) after mechanical unloading. EHTs were created by seeding decellularized porcine myocardial sections with a mixture of primary neonatal rat ventricular myocytes and cardiac fibroblasts. Each end of the ribbon-like constructs was fixed to a plastic clip, allowing the tissues to be statically stretched or slackened. Inelastic deformation was introduced by stretching tissues by 20% of their original length. EHTs were subsequently unloaded by returning tissues to their original, shorter length. Mechanical characterization of EHTs immediately after unloading and at subsequent time points confirmed the presence of a reverse-remodeling process, through which stress-free tissue length was increased after chronic stretch but gradually decreased back to its original value within 9 days. When a cardiac myosin inhibitor was applied to tissues after unloading, EHTs failed to completely recover their passive and active mechanical properties, suggesting a role for actomyosin contraction in reverse remodeling. Selectively inhibiting cardiomyocyte contraction or fibroblast activity after mechanical unloading showed that contractile activity of both cell types was required to achieve full remodeling. Similar tests with EHTs formed from human induced pluripotent stem cell-derived cardiomyocytes also showed reverse remodeling that was enhanced when treated with omecamtiv mecarbil, a myosin activator. These experiments suggest essential roles for active sarcomeric contraction and fibroblast activity in reverse remodeling of myocardium after mechanical unloading. Our findings provide a mechanistic rationale for designing potential therapies to encourage reverse remodeling in patient hearts.

Endothelial Zeb2 preserves the hepatic angioarchitecture and protects against liver fibrosis

Aims

Hepatic capillaries are lined with specialized liver sinusoidal endothelial cells (LSECs) which support macromolecule passage to hepatocytes and prevent fibrosis by keeping hepatic stellate cells (HSCs) quiescent. LSEC specialization is co-determined by transcription factors. The zinc-finger E-box-binding homeobox (Zeb)2 transcription factor is enriched in LSECs. Here, we aimed to elucidate the endothelium-specific role of Zeb2 during maintenance of the liver and in liver fibrosis.

Methods and results

To study the role of Zeb2 in liver endothelium we generated EC-specific Zeb2 knock-out (EC^KO) mice. Sequencing of liver EC RNA revealed that deficiency of Zeb2 results in prominent expression changes in angiogenesis-related genes. Accordingly, the vascular area was expanded and the presence of pillars inside EC^KO liver vessels indicated that this was likely due to increased intussusceptive angiogenesis. LSEC marker expression was not profoundly affected and fenestrations were preserved upon Zeb2 deficiency. However, an increase in continuous EC markers suggested that Zeb2-deficient LSECs are more prone to dedifferentiation, a process called ‘capillarization’. Changes in the endothelial expression of ligands that may be involved in HSC quiescence together with significant changes in the expression profile of HSCs showed that Zeb2 regulates LSEC–HSC communication and HSC activation. Accordingly, upon exposure to the hepatotoxin carbon tetrachloride (CCl₄), livers of EC^KO mice showed increased capillarization, HSC activation, and fibrosis compared to livers from wild-type littermates. The vascular maintenance and anti-fibrotic role of endothelial Zeb2 was confirmed in mice with EC-specific overexpression of Zeb2, as the latter resulted in reduced vascularity and attenuated CCl₄-induced liver fibrosis.

Conclusion

Endothelial Zeb2 preserves liver angioarchitecture and protects against liver fibrosis. Zeb2 and Zeb2-dependent genes in liver ECs may be exploited to design novel therapeutic strategies to attenuate hepatic fibrosis.

Angiodiversity and organotypic functions of sinusoidal endothelial cells

‘Angiodiversity’ refers to the structural and functional heterogeneity of endothelial cells (EC) along the segments of the vascular tree and especially within the microvascular beds of different organs. Organotypically differentiated EC ranging from continuous, barrier-forming endothelium to discontinuous, fenestrated endothelium perform organ-specific functions such as the maintenance of the tightly sealed blood–brain barrier or the clearance of macromolecular waste products from the peripheral blood by liver EC-expressed scavenger receptors. The microvascular bed of the liver, composed of discontinuous, fenestrated liver sinusoidal endothelial cells (LSEC), is a prime example of organ-specific angiodiversity. Anatomy and development of LSEC have been extensively studied by electron microscopy as well as linage-tracing experiments. Recent advances in cell isolation and bulk transcriptomics or single-cell RNA sequencing techniques allowed the identification of distinct LSEC molecular programs and have led to the identification of LSEC subpopulations. LSEC execute homeostatic functions such as fine tuning the vascular tone, clearing noxious substances from the circulation, and modulating immunoregulatory mechanisms. In recent years, the identification and functional analysis of LSEC-derived angiocrine signals, which control liver homeostasis and disease pathogenesis in an instructive manner, marks a major change of paradigm in the understanding of liver function in health and disease. This review summarizes recent advances in the understanding of liver vascular angiodiversity and the functional consequences resulting thereof.

Endothelial to Mesenchymal Transition in the Cardiogenesis and Cardiovascular Diseases

Today, cardiovascular diseases remain a leading cause of morbidity and mortality worldwide. Endothelial to mesenchymal transition (EndMT) does not only play a major role in the course of development but also contributes to several cardiovascular diseases in adulthood. EndMT is characterized by down-regulation of the endothelial proteins and highly up-regulated fibrotic specific genes and extracellular matrix-forming proteins. EndMT is also a transforming growth factor-β-driven (TGF-β) process in which endothelial cells lose their endothelial characteristics and acquire a mesenchymal phenotype with expression of α-smooth muscle actin (α-SMA), fibroblast-specific protein 1, etc. EndMT is a vital process during cardiac development, thus disrupted EndMT gives rise to the congenital heart diseases, namely septal defects and valve abnormalities. In this review, we have discussed the main signaling pathways and mechanisms participating in the process of EndMT such as TGF-β and Bone morphogenetic protein (BMP), Wnt^#, and Notch signaling pathway and also studied the role of EndMT in physiological cardiovascular development and pathological conditions including myocardial infarction, pulmonary arterial hypertension, congenital heart defects, cardiac fibrosis, and atherosclerosis. As a perspective view, having a clear understanding of involving cellular and molecular mechanisms in EndMT and conducting Randomized controlled trials (RCTs) with a large number of samples for involving pharmacological agents may guide us into novel therapeutic approaches of congenital disorders and heart diseases.

Endothelial GATA4 controls liver fibrosis and regeneration by preventing a pathogenic switch in angiocrine signaling

BACKGROUND & AIMS

Angiocrine signaling by liver sinusoidal endothelial cells (LSECs) regulates hepatic functions such as growth, metabolic maturation, and regeneration. Recently, we identified GATA4 as the master regulator of LSEC specification during development. Herein, we studied the role of endothelial GATA4 in the adult liver and in hepatic pathogenesis.

METHODS

We generated adult Clec4g-icre^tg/0xGata4^fl/fl (Gata4^LSEC-KO) mice with LSEC-specific depletion of Gata4. Livers were analyzed by histology, electron microscopy, immunohistochemistry/immunofluorescence, in situ hybridization, and LSECs were isolated for gene expression profiling, ChIP- and ATAC-sequencing. Partial hepatectomy was performed to assess regeneration. We used choline-deficient, l-amino acid-defined (CDAA) diet and chronic carbon tetrachloride exposure to model liver fibrosis. Human single cell RNA-seq data sets were analyzed for endothelial alterations in healthy and cirrhotic livers.

RESULTS

Genetic Gata4 deficiency in LSECs of adult mice caused perisinusoidal liver fibrosis, hepatopathy and impaired liver regeneration. Sinusoidal capillarization and LSEC-to-continuous endothelial transdifferentiation were accompanied by a profibrotic angiocrine switch involving de novo endothelial expression of hepatic stellate cell-activating cytokine PDGFB. Increased chromatin accessibility and amplification by activated MYC mediated angiocrine Pdgfb expression. As observed in Gata4^LSEC-KO livers, CDAA diet-induced perisinusoidal liver fibrosis was associated with GATA4 repression, MYC activation and a profibrotic angiocrine switch in LSECs. Comparison of CDAA-fed Gata4^LSEC-KO and control mice demonstrated that endothelial GATA4 indeed protects against dietary-induced perisinusoidal liver fibrosis. In human cirrhotic livers, GATA4-positive LSECs and endothelial GATA4 target genes were reduced, while non-LSEC endothelial cells and MYC target genes including PDGFB were enriched.

CONCLUSIONS

Endothelial GATA4 protects against perisinusoidal liver fibrosis by repressing MYC activation and profibrotic angiocrine signaling at the chromatin level. Therapies targeting the GATA4/MYC/PDGFB/PDGFRβ axis offer a promising strategy for prevention and treatment of liver fibrosis.

LAY SUMMARY

The liver vasculature is supposed to play a major role in the development of liver fibrosis and cirrhosis, which can lead to liver failure and liver cancer. Herein, we discovered that structural and transcriptional changes induced by genetic deletion of the transcription factor GATA4 in the hepatic endothelium were sufficient to cause liver fibrosis. Activation of the transcription factor MYC and de novo expression of the "angiocrine" growth factor PDGFB were identified as downstream drivers of fibrosis and as potential therapeutic targets for this potentially fatal disease.

The E-Twenty-Six Family in Hepatocellular Carcinoma: Moving into the Spotlight

Hepatocellular carcinoma (HCC) is a major cause of morbidity and mortality worldwide. Although therapeutic strategies have recently advanced, tumor metastasis and drug resistance continue to pose challenges in the treatment of HCC. Therefore, new molecular targets are needed to develop novel therapeutic strategies for this cancer. E-twenty-six (ETS) transcription family has been implicated in human malignancies pathogenesis and progression, including leukemia, Ewing sarcoma, gastrointestinal stromal tumors. Recently, increasing studies have expanded its great potential as functional players in other cancers, including HCC. This review focuses primarily on the key functions and molecular mechanisms of ETS factors in HCC. Elucidating these molecular details may provide novel potential therapeutic strategies for cancers.